Handheld machining device, particularly for boring

ABSTRACT

A handheld machining device ( 1 ), particularly for boring, having a mechanism includes: a first mounting ( 20 ), on which a tool holder ( 2 ), and a motor ( 3, 4 ) arranged to rotate the tool holder ( 2 ), are mounted; a second mounting ( 30 ); and an element ( 40 ) for translatably guiding, between the first mounting ( 20 ) and the second mounting ( 30 ), a linear actuator ( 5 ) enabling the first mounting ( 20 ) to be spaced apart from the second mounting ( 30 ), and the first mounting ( 20 ) to be brought toward the second mounting ( 30 ). The motor ( 3, 4 ) is electric, and the rotor ( 4 ) of the first motor ( 3, 4 ) is directly mounted onto the tool holder ( 2 ) and is rigidly connected thereto.

The invention relates to a handheld machining device, more particularlyfor boring.

In the field of handheld boring tools, in particular in aeronautics,handheld boring tools are known that make it possible not only to rotatethe cutting tool, but also to move the cutting tool forwards orbackwards, in a controlled manner, thanks to a linear actuator of saidhandheld tool.

It is known in prior art for example documents EP-2.108.478 orWO-2009/128757 of such handheld tools. In the devices of these twodocuments, a first motor makes it possible, by the intermediary of ascrew/nut system to control the forward movement or backward movement ofthe cutting tool, while a second motor makes it possible to transmit aspin torque to the cutting tool, by the intermediary of a spline shafttransmission. In the devices of these two documents, the first motor andthe second motor are fixed in relation to one another. The second motor,transmitting the spin torque to the tool, is rigidly connected to thecase of the mechanism.

It is also known from the state of the art document US-2006/0269369 ahandheld machining device that combines, on the one hand a pneumaticmotor in order to rotate a cutting tool, and on the other hand a linearactuator comprising a ball screw and an electric motor, of the steppingtype enabling the simultaneous displacement in translation of the unitformed by the pneumatic motor and cutting tool, forwards and backwards.In the device of this document, the pneumatic motor and the electricmotor are displaced in translation, in relation to one another, duringthe forward movement or backward movement of the cutting tool.

In the device of this document US-2006/0269369, the electric motor, ofthe stepping type, is coupled to an angular encoder which produces asignal that represents the position of the linear actuator. This signalis used by control electronics allowing the control of the electricmotor of the linear actuator. These electronics are a separate elementand distinct from the handheld device, connected in particular to theelectric motor of the tool by means of a flexible electric cable. Usinga pneumatic motor requires in order to rotate the cutting tool at lowspeeds (less than 8000 rpm) the provision of a reducer between the tooland the output of the motor. Such a device does not enable any controlof the rotation of the cutting tool.

The purpose of this invention is to propose a handheld machining devicemaking it possible to obtain cutting precisions down to the micron,improved performance as to known prior art.

Other purposes and advantages of this invention shall appear in thefollowing description, which is provided only for the purposes ofinformation and which does not have for purpose to limit it.

The invention relates to a handheld machining device, in particular forboring, having a mechanism comprising:

-   -   a first mounting which carries:        -   a tool holder,        -   a motor arranged to rotate the tool holder,    -   a second mounting and means for translatably guiding between the        first mounting and said second mounting,    -   a linear actuator enabling the first mounting to be spaced apart        from second mounting and the first mounting to be brought toward        said second mounting.

According to the invention, said motor is an electric motor and therotor of the motor is directly mounted onto the tool holder, rigidlyconnected to said tool holder.

According to optional characteristics, taken individually or incombination:

-   -   the rotor of the motor is exterior to the stator of said motor;    -   said motor is said first motor and said linear actuator        comprises a ball screw system and a second motor;    -   the second motor is an electric motor and the rotor of the        second motor is directly mounted onto the screw of the linear        actuator, rigidly connected to said screw.    -   the second mounting carries said second motor, the stator of        said second motor being integral in translation with said second        mounting, the nut of the ball screw system being integral in        translation with said first mounting, or alternatively:    -   the first mounting carries said second motor, the stator of said        second motor being integral in translation with said first        mounting, the nut of the ball screw system being integral in        translation with said second mounting;    -   the rotor of said second motor is exterior to the stator of said        second motor;    -   the axis of rotation of the tool holder and the axis of rotation        of the screw of the ball screw system are parallel and        confounded;    -   the axis of rotation of the tool holder and the axis of rotation        of the screw of the ball screw system are parallel and not        confounded, said unit formed by the tool holder and first motor        being positioned juxtaposed laterally to said linear actuator.    -   the device has an angular encoder targeting the rotation of the        screw of the ball screw system, as well as power and control        electronics for controlling said first motor and said second        motor having for input the signal emitted by said angular        encoder;    -   the device has, in addition to the angular encoder targeting the        rotation of the screw, said first angular encoder, a second        angular encoder targeting the rotation of said tool holder, said        power and control electronics for controlling said first motor        and said second motor having for input, in addition to the        signal emitted by the first angular encoder, the signal emitted        by said second angular encoder;    -   said mechanism is integrated into a case in particular provided        with a handle, said power and control electronics being interior        and integrated into said case of said handheld device;    -   the tool holder has a rotating shaft integral with the rotor        motor said rotating shaft having a duct for a fluid intended to        lubricate a cutting tool, as well as a rotating seal providing        the seal between one end of the rotating shaft and an inlet port        for the fluid;    -   said linear actuator is comprised of a linear motor.

The invention shall be better understood when reading the followingdescription accompanied by a single annexed figure whichdiagrammatically shows the mechanism of the handheld tool in accordancewith the invention, according to an embodiment.

Also, the invention relates to a handheld machining device 1, inparticular for boring, having a mechanism comprising:

-   -   a first mounting 20 which carries:        -   a tool holder 2,        -   a motor 3, 4 arranged to rotate the tool holder 2,    -   a second mounting 30 and means 40 for translatably guiding        between the first mounting 20 and said second mounting 30,    -   a linear actuator 5 enabling the first mounting 20 to be spaced        apart from said second mounting 30 and the first mounting 20 to        be brought toward said second mounting 30.

According to the invention, the motor 3, 4 is an electric motor and therotor 4 of the motor 3, 4 is directly mounted onto the tool holder 2,rigidly connected to said tool holder 2.

The direct mounting of the rotor 4 onto the tool holder 2 makes itpossible to eliminate the presence of a reduction gear between these twoelements 2, 4, making it possible not only to reduce the encumbrance ofthe device 1 but also to avoid the presence of a gap inherent to thegears of a reducer.

The rotor 4 of the motor 3, 4 can be exterior to the stator 3 of saidmotor 3, 4. The use of an external rotor motor for the motor 3, 4 makesit possible to limit the number of bearings 19 for the simultaneousguiding in rotation of the rotor 4.

According to the invention, the linear actuator 5 makes it possible assuch to displace in translation at least the unit formed by the toolholder 2 and motor 3, 4. The motor 3, 4 makes it possible to rotate thetool holder 2, of which the axis of rotation is parallel to the axis ofdisplacement of the linear actuator 5.

Of course, this mechanism can be integrated into a case in particularmade of plastic, and in particular provided with one or severalhandles(s) (not shown) allowing an operator to manipulate the handhelddevice. One of the handles can in particular be provided with a controltrigger (not shown) in a manner known per se, in order to actuate themachining.

According to an embodiment, said motor 3, 4 is said first motor 3, 4 andsaid linear actuator 5 comprises a ball screw system 6, 7 and a secondmotor 8, 9. According to the example embodiment shown in FIG. 1, thesecond motor 8, 9 can be an electric motor and the rotor 9 of the secondmotor 8, 9 is directly mounted onto the screw 6 of the linear actuator5, rigidly connected to said screw 6.

The direct mounting of the rotor 9 of the second motor 8, 9 onto thescrew 6 makes it possible to avoid the presence of a reducer betweenthese two elements making it possible to limit the encumbrance of thedevice, but also to avoid the presence of a gap inherent to the gears ofa reducer.

According to an embodiment shown, the rotor 9 of said second motor 8, 9can be exterior to the stator 8 of said second motor.

The use of an external rotor motor for the second motor 8, 9 makes itpossible to limit the number of bearings 20 for the simultaneous guidingin rotation of the rotor 9 and of the screw 6.

The motors, utilised for the first motor 3, 4 and/or the second motor 8,2 can be high-performance brushless electric motors and of low voltage(less than 48 volts). These motors have very advantageous power/weightperformance (greater than 5 W/g) and use magnet technologies with a highCurie point (about 200°) and winding wires of which the insulators canwithstand temperatures of 180° C. Such motors are in particular marketedby the Company Scorpion Power System Ltd.

According to an embodiment shown in FIG. 1, the second mounting 30carries said second motor 8, 9, the stator 9 of said second motor 8, 9being integral in translation with said second mounting 30, the nut 7 ofthe ball screw system 6, 7 being integral in translation with said firstmounting 20. Alternatively according to an embodiment not shown thefirst mounting 20 carries said second motor 8, 9, the stator 9 of saidsecond motor 8, 9 with integral in translation with said first mounting20, the nut 7 of the ball screw system 6, 7 being integral intranslation with said second mounting 30.

According to an embodiment shown in FIG. 1, the axis of rotation 10 ofthe tool holder of the axis of rotation 11 of the screw 6 of the ballscrew system 6, 7 are parallel and confounded. Alternatively, accordingto an embodiment not shown, of less encumbrance, the axis of rotation ofthe tool holder 2 and the axis of rotation of the screw 6 of the ballscrew system 6, 7 can be parallel and not confounded, said unit formedby the tool holder 2 and first motor 3, 4 being positioned juxtaposedlaterally to said linear actuator 5.

According to an embodiment, shown in FIG. 1, the tool holder 2 has arotating shaft 12 integral with the rotor 4 of the first motor 3, 4,said rotating shaft having a duct 13 for a fluid intended to lubricatethe cutting tool 14, as well as a rotating seal 15 providing the sealbetween one end of the rotating shaft 12 and an inlet port 16 for thefluid.

According to this example, the cutting tool 14 can be provided with aninternal duct intended to channel the fluid from the duct 13 of therotating shaft to the cutting edge of the cutting tool 14.

The device 1 can have an angular encoder 17 targeting the rotation ofthe screw 6 of the ball screw system 6, 7 as well as power and controlelectronics (not shown) for the control of said first motor 3, 4 and ofthe second motor 8, 9 comprising for input at least the signal emittedby said angular encoder 17. Advantageously, these electronics can beintegrated into the case of the handheld tool, interior to this case.

The handheld tool can have, in addition to the angular encoder 17targeting the rotation of the screw 6, said first angular encoder, asecond angular encoder 18 targeting the rotation of the tool holder 2.

The power and control electronics for controlling the first motor 3, 4and the second motor 8, 9 has then for inputs, in addition to the signalemitted by the first angular encoder 17, the signal emitted by saidsecond angular encoder 18.

The embodiment shown in FIG. 1 shall now be described in detail.

The mechanism of the handheld machining device comprises a first hollowmounting 20, this mounting interiorly receives a rotating shaft 12guided in rotation thanks to two ball bearings 19, provided between saidshaft and the mounting 20. This shaft 12 is rigidly integral, on the onehand, with a tool holder 2 to which is rigidly connected a cutting tool14, and on the other hand rigidly integral with a rotor 4 of said firstmotor 3, 4. The stator 3 of the first motor 3, 4 is rigidly integralwith the mounting 20. An angular encoder 18 makes it possible to targetthe rotation of the shaft 12.

This rotating shaft 12 is hollow and constitutes a duct 13 for a fluidintended to lubricate the cutting tool 14. One of the ends of the duct13 is associated to a rotating seal 15 which makes it possible toprovide the seal between the end of the shaft 12 and an inlet port 16 ofthe mounting 20. The duct of the shaft 12 of the tool holder 2 isextended interiorly into the cutting tool 14, the duct 13 opening on thecutting edge of the tool 14.

The second motor 8, 9 of the linear actuator 5 is provided on a secondmounting 30. The stator 8 of the second motor 8, 9 is interior to therotor 9. The stator 8 is integral with the second mounting 30. The rotor9, external to the stator 8, is mounted rotating guided in rotationthanks to a ball bearing 19 between the shaft of the motor.

The rotor 9 of the second motor 8, 9 is rigidly integral with the screw6 of the ball screw system 6. The nut 7 of the ball screw system 6, 7 isintegral with the first mounting 20. A sliding connection (said meansfor translatably guiding 40) with axis parallel to the axis of the ballscrew 6 is provided between the first mounting 20 and the secondmounting 30. This sliding connection makes it possible to guide intranslation the unit comprising the first mounting 20, the first motor3, 4 and the cutting tool 14 in relation to the unit comprising thesecond mounting 30 and the second motor 8, 9. An angular encoder 17makes it possible to target the rotation of the rotating shaft of saidsecond motor 8, 9.

According to an embodiment (not shown) the linear actuator 5 comprisedaccording to the example of the ball screw system 6, 7 and said secondmotor 8, 9 can be replaced with a linear actuator comprised of a linearmotor.

According to this embodiment, the device can have a linear encodertargeting the displacement of the first mounting in relation to secondmounting, as well as power and control electronics (not shown) forcontrolling, on the one hand, the motor arranged to rotate the toolholder and, on the other hand, the controlling of said linear motor.These electronics comprise for input at least the signal emitted by thelinear encoder.

Advantageously, these electronics can be integrated into the case of thehandheld device receiving the mechanism, interior to this case.

The handheld device can have, in addition to the linear encodertargeting the displacement of the first mounting in relation to secondmounting, an angular encoder targeting the rotation of the tool holder.The power and control electronics then have for input, in addition tothe signal emitted by the linear encoder, the signal emitted by theangular encoder.

Naturally, other embodiments could have been considered by those skilledin the art without however leaving the scope of the invention defined bythe claims hereinafter.

1. Handheld machining device (1), in particular for boring, having amechanism comprising: a first mounting (20) which carries: a tool holder(2), a motor (3, 4) arranged to rotate the tool holder (2), a secondmounting (30) and means for translatably guiding (40) between the firstmounting (20) and said second mounting (30), a linear actuator (5)enabling the first mounting (20) to be spaced apart from the said secondmounting (30) and the first mounting (20) to be brought toward saidsecond mounting (30) characterised in that the motor (3, 4) is anelectric motor and the rotor (4) of the motor (3, 4) is directly mountedonto the tool holder (2), rigidly integral with said tool holder (2). 2.Device according to claim 1, wherein the rotor (4) of the motor (3, 4)is exterior to the stator (3) of said motor.
 3. Device according toclaim 1, wherein said motor (3, 4) is said first motor (3, 4) andwherein said linear actuator (5) comprises a ball screw system (6, 7)and a second motor (8, 9).
 4. Device according to claim 3, wherein thesecond motor is an electric motor and wherein the rotor (9) of thesecond motor (8, 9) is directly mounted onto the screw (6) of the linearactuator (5), rigidly integral with said screw (6).
 5. Device accordingto claim 3, wherein the second mounting (30) carries said second motor(8, 9), the stator (9) of said second motor (8, 9) being integral intranslation with said second mounting (30), the nut (7) of the ballscrew system (6, 7) being integral in translation with said firstmounting (20).
 6. Device according to claim 3 wherein the first mounting(20) carries said second motor (8, 9), the stator (9) of said secondmotor (8, 9) being integral in translation with said first mounting(20), the nut (7) of the ball screw system (6, 7) being integral intranslation with said second mounting (30).
 7. Device according to claim3, wherein the rotor (9) of said second motor (8, 9) is exterior to thestator (8) of said second motor.
 8. Device according to claim 3, whereinthe axis of rotation (10) of the tool holder (2) and the axis ofrotation (11) of the screw (6) of the ball screw system (6, 7) areparallel and confounded.
 9. Device according to claim 3, wherein theaxis of rotation of the tool holder (2) and the axis of rotation of thescrew (6) of the ball screw system (6, 7) are parallel and notconfounded, said unit formed by tool holder (2) and first motor (3, 4)being positioned juxtaposed laterally to said linear actuator (5). 10.Device according to claim 3, having an angular encoder (17) targetingthe rotation of the screw (6) of the ball screw system (6, 7), as wellas power and control electronics for controlling said first motor (3, 4)and said second motor (8, 9) having for input the signal emitted by saidangular encoder (17).
 11. Device according to claim 10, having, inaddition to the angular encoder (17) targeting the rotation of the screw(6), said first angular encoder, a second angular encoder (18) targetingthe rotation of said tool holder (2), said power and control electronicsfor controlling said first motor (3, 4) and second motor (8, 9) havingfor input, in addition to the signal emitted by the first angularencoder (17), the signal emitted by said second angular encoder (18).12. Device according to claim 10, wherein said mechanism is integratedinto a case in particular provided with a handle, said power and controlelectronics being interior and integrated into said case of saidhandheld device.
 13. Device according to claim 1, the tool holder has arotating shaft (12) integral with the rotor (4) of the motor (3, 4),said first motor, said rotating shaft (12) having a duct (13) for afluid intended to lubricate a cutting tool (14), as well as a rotatingseal (15) providing the seal between one end of the rotating shaft (12)and an inlet port (16) for the fluid.
 14. Device according to claim 1,wherein said linear actuator is comprised of a linear motor.
 15. Deviceaccording to claim 2, wherein said motor (3, 4) is said first motor (3,4) and wherein said linear actuator (5) comprises a ball screw system(6, 7) and a second motor (8, 9).
 16. Device according to claim 4,wherein the second mounting (30) carries said second motor (8, 9), thestator (9) of said second motor (8, 9) being integral in translationwith said second mounting (30), the nut (7) of the ball screw system (6,7) being integral in translation with said first mounting (20). 17.Device according to claim 4 wherein the first mounting (20) carries saidsecond motor (8, 9), the stator (9) of said second motor (8, 9) beingintegral in translation with said first mounting (20), the nut (7) ofthe ball screw system (6, 7) being integral in translation with saidsecond mounting (30).
 18. Device according to claim 11, wherein saidmechanism is integrated into a case in particular provided with ahandle, said power and control electronics being interior and integratedinto said case of said handheld device.
 19. Device according to claim 2,wherein said linear actuator is comprised of a linear motor.
 20. Deviceaccording to claim 13, wherein said linear actuator is comprised of alinear motor.